1. SECTION 10.2
Angles and Arcs

2. ANGLE AND ARCS
 What are the major arcs, minor arcs, semicircles
and central angles and their measures?

3. CENTRAL ANGLE
 Central Angle: An angle with the center of the circle
as the vertex and radii as the sides.

4. CENTRAL ANGLE
 Sum of Central Angles =

5. CENTRAL ANGLE


6. TYPES OF ARCS
 Measurement of an Arc = Measurement of the
central Angle
 Minor: < 180°
 Semi-circle: = 180°
 Major: > 180°

7. EXAMPLE


8. EXAMPLE


9. EXAMPLE


10. HOMEWORK
 Page 533
 14 - 31

11. ANGLE AND ARCS
 How can I calculate arc measure?
 How can I calculate arc length?

12. EXAMPLE
 Find the measure of each central angle.

13. ARC LENGTH
 Another way to measure an arc
 A fraction of the circumference
 Proportion:
Degree measure
of central angle Arc length
Degrees in a circle Circumference
of a circle

14. EXAMPLE


15. EXAMPLE


16. HOMEWORK
 Page 533
 32 - 52

17. LESSON PLAN
 Intro
 Splitting a circle in pieces of pie.
 Standards-
 Supplies – slides, whiteboard, note sheets
 Timing: Two days with notes and homework. A third day will
be review and a fourth with a quiz.
 Day 1:
 Essential Questions- slides 2
 Input-slides 3-6
 Guided Practice - slides 7, 8, and 9
 Independent Practice – Book Work
 Day 2:
 Essential Questions- slides 11
 Input-slides 13
 Guided Practice - slides 12 and 14 and 15
 Independent Practice – Book Work